A liquid supply device includes a mobile body having a supply head and, for example, supplies liquid from the supply head onto a substrate that serves as a work piece to form a liquid applied portion, which has a predetermined pattern. In such a liquid supply device, the mobile body must always be arranged at a position constantly spaced by a predetermined distance from the surface of the substrate to form a uniform liquid applied portion. In the prior art, for example, patent document 1 proposes a rough and fine movement device that fulfills such a requirement.
In the rough and fine movement device of the prior art, two rails are arranged on a base to movably support a first mobile body and a second mobile body. A feed screw is arranged on the base. A nut is fixed to the first mobile body and mated with the feed screw. A piezoelectric element is arranged between the first mobile body and second mobile body. Further, two coil springs connect the two mobile bodies. A drive motor rotates the feed screw to roughly move the first mobile body and the second mobile body in large strokes. Voltage is applied to the piezoelectric element in a state in which the rough movement is stopped to expand or contract the piezoelectric element so as to finely move the second mobile body in fine strokes relative to the first mobile body. Such movements enable fine adjustments when positioning a moved member, which is held on the second mobile body, at a predetermined position.
However, in the rough and fine movement device of the prior art, for example, low machining accuracy or low assembly accuracy of the feed screw may affect the second mobile body from the first mobile body through the piezoelectric element. In such a case, the second mobile body cannot be moved to the required position with high accuracy even if the accuracy of the rails is ensured. In the rough and fine movement device of patent document 1, there have been no measures coping with such a problem. Thus, the accuracy for moving the second mobile body to the desired position is low.
Patent Document 1: Japanese Laid-Open Utility Model Publication No. 5-66592